The present invention relates to plugs for gripping and forming fluid-tight seals within inner peripheries of pipes, pipelines, tubes, pressure vessels and the like adjacent open ends thereof. More specifically, the present invention relates to test plugs that are able to reliably and safely form seals in pipe elbows for use in hydrotesting open end pipe elbows. The same test plug may also be capable of use in other tests and with other pipe configurations and fittings.
The plugs, for instance, may include hydrostatic test plugs, vacuum test plugs or the like for use in pressure testing pipes, pipelines, tubes, pressure vessels, pressure retaining components, and the like. The test plugs are used when performing leak tests or to verify structural integrity or strength of pipes, pipelines, tubes, pressure vessels, flange-to-pipe connections, pipe-to-pipe connections, and the like. Depending upon the material, size and thickness of the pipe and the pressure rating of the pipe, a test plug used to form a seal adjacent an open end of a pipe must be able to withstand at least the pressure rating of the pipe and must be able to resist movement, sliding, failure, blow-out and/or leakage during working pressures and must not damage the pipe.
Pipe system fabrication shops that assemble piping for customers, for instance, in the oil, gas, and chemical processing industries, have typically found it challenging to test, for instance, hydro-test, piping having an end that terminates with an open elbow joint. This is because an uncompromised tight seal is essential for accurate testing and safety, and elbow joints have inner wall geometries that make it difficult to obtain an uncompromised tight seal. Conventional and standard test plugs typically do not properly fit into an elbow pipe and are unable to form the required seal and grip.
A conventional solution to the above referenced problem has been to weld a separate piece of straight pipe to an elbow joint solely to enable testing so that a standard test plug may be installed for testing. After the test has been completed, the extra piece of straight pipe is removed and the elbow must be properly dressed to comply with engineering specifications. Thus, significant time and effort is necessary for temporarily adding and then removing such straight pieces of pipe.